Commitments, Contingencies and Guarantees - Commitments (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Commitment Liabilities [Line Items]
Total commitments to extend credit	$ 115,062	$ 112,056
Contingent and forward starting resale and securities borrowing agreements	42,366	25,348
Forward starting repurchase and secured lending agreements	17,827	8,939
Letters of credit	406	373
Investment commitments	8,602	8,444
Other	4,848	6,014
Total commitments	189,111	161,174
Maturities, Year 1 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	16,282
Contingent and forward starting resale and securities borrowing agreements	42,363
Forward starting repurchase and secured lending agreements	17,827
Letters of credit	184
Investment commitments	5,360
Other	4,478
Total commitments	86,494
Maturities, Year 2 and Year 3 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	26,912
Contingent and forward starting resale and securities borrowing agreements	3
Letters of credit	182
Investment commitments	612
Other	311
Total commitments	28,020
Maturities, Year 3 and Year 4 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	55,338
Investment commitments	107
Other	16
Total commitments	55,461
Maturities, Year 5 and Thereafter [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	16,530
Letters of credit	40
Investment commitments	2,523
Other	43
Total commitments	19,136
Investment Grade Commercial Lending [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	74,351	73,664
Investment Grade Commercial Lending [Member] | Maturities, Year 1 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	14,774
Investment Grade Commercial Lending [Member] | Maturities, Year 2 and Year 3 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	16,661
Investment Grade Commercial Lending [Member] | Maturities, Year 3 and Year 4 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	37,047
Investment Grade Commercial Lending [Member] | Maturities, Year 5 and Thereafter [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	5,869
Non Investment Grade Commercial Lending [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	36,930	34,878
Non Investment Grade Commercial Lending [Member] | Maturities, Year 1 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	1,438
Non Investment Grade Commercial Lending [Member] | Maturities, Year 2 and Year 3 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	8,600
Non Investment Grade Commercial Lending [Member] | Maturities, Year 3 and Year 4 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	17,319
Non Investment Grade Commercial Lending [Member] | Maturities, Year 5 and Thereafter [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	9,573
Warehouse Financing [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	3,781	$ 3,514
Warehouse Financing [Member] | Maturities, Year 1 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	70
Warehouse Financing [Member] | Maturities, Year 2 and Year 3 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	1,651
Warehouse Financing [Member] | Maturities, Year 3 and Year 4 [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	972
Warehouse Financing [Member] | Maturities, Year 5 and Thereafter [Member]
Commitment Liabilities [Line Items]
Total commitments to extend credit	$ 1,088